Allow Icon + Label on buttons
While we don't recommend having both icon and label on buttons in most cases, there are specific instances where it makes sense (e.g. "Record" button in Sound Recorder), so we definitely want it to be technically possible to do in GTK.
Also, for the stylesheet refresh we want to simplify headerbar buttons, the current proposal for which will require icon + label buttons in some places.
As far as I understood from what @exalm said, GTK4 currently doesn't allow defining icon + label buttons in an easy way. It'd be good to fix this before the style refresh lands with libadwaita 1.0 later this year.